NCP81231 High Resolution Buck Controller with Full USB PD Features and 100% Duty Operation www.onsemi.com The NCP81231 is a synchronous buck that is optimized for converting battery voltage or adaptor voltage into power supply rails required in notebook, tablet, and desktop systems, as well as many other consumer devices using USB PD standard and C−Type cables. The NCP81231 is fully compliant to the USB Power Delivery Specification when used in conjunction with a USB PD or C−Type Interface Controller. NCP81231 is designed for applications requiring dynamically controlled slew rate limited output voltage. Features • • • • • • • • • • • • • • • • Wide Input Voltage Range: from 4.5 V to 28 V Dynamically Programmed Frequency from 150 kHz to 1.2 MHz I2C Interface Real Time Power Good Indication Controlled Slew Rate Voltage Transitioning Feedback Pin with Internally Programmed Reference High Resolution DAC Voltage Two Independent Current Sensing Inputs Support Inductor DCR Sensing Over Temperature Protection Adaptive Non−Overlap Gate Drivers Filter Capacitor Switch Control 100% Duty Cycle Operation Latched Over−Voltage and Over−Current Protection Dead Battery Power Support 5 x 5 mm QFN32 Package Notebooks, Tablets, Desktops Gaming Monitors, TVs, and Set Top Boxes Consumer Electronics Car Chargers Docking Stations Power Banks © Semiconductor Components Industries, LLC, 2016 December, 2017 − Rev. 1 32 QFN32 5x5, 0.5P CASE 485CE MARKING DIAGRAM Typical Application • • • • • • • 1 1 1 NCP81231 AWLYYWWG G A = Assembly Location WL = Wafer Lot YY = Year WW = Work Week G = Pb−Free Package (Note: Microdot may be in either location) ORDERING INFORMATION Device NCP81231MNTXG Package QFN32 (Pb−Free) Shipping† 4000 / Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. Publication Order Number: NCP81231/D NCP81231 V1 V2 DBIN V1 DBOUT CSP1 VDRV CSN1 CVDRV Q6 FB RDRV RPU CSN2 CO1 VCC CO2 CVCC RPD CSP2 Current Sense 1 CS 1 Q5 CFET1 RCS 1 Current Sense 2 CS 2 BST 1 RCS 2 Q1 CLIND Curret Limit Indicator Interrupt INT Enable EN CB1 HSG1 VSW 1 L1 SDA I2C SCL Q2 LSG1 COMP PGND1 RC VOUT CP CC AGND PDRV Figure 1. Typical Application Circuit (DCR) www.onsemi.com 2 VBUS NCP81231 V1 V2 V1 DBIN DBOUT CSP1 VDRV CSN1 CVDRV Q6 FB RDRV RPU CSN2 CO1 VCC CO2 CVCC RPD CSP2 Current Sense 1 CS 1 Q5 CFET1 RCS 1 Current Sense 2 CS 2 BST 1 RCS 2 Q1 CLIND Curret Limit Indicator Interrupt INT Enable EN CB1 HSG1 VSW 1 L1 SDA I2C SCL Q2 LSG1 PGND1 COMP RC VOUT CP PDRV BST1 VSW1 VCC VDRV DBIN DBOUT VOUT NC Figure 2. Typical Application Circuit (Rsense) 32 31 30 29 28 27 26 25 23 NC PGND1 3 22 PGND2 CSN1 4 21 CSP2 CSP1 5 20 CSN2 V1 6 19 FB CS1 7 18 CS2 CLIND 8 17 PDRV 10 SCL 9 11 12 13 14 15 16 EN 2 COMP LSG1 AGND NC AGND 24 CFET 1 INT HSG1 SDA CC AGND Figure 3. Pinout www.onsemi.com 3 VBUS NCP81231 V1 DBOUT V1 V1 Current Limiting Circuit For Dead Battery IUVLOB VDRV_rdy Protection Driver Control Logic CS 2_INT CLINDP1 + CS2 HSG1 CS 1_INT − CS 1 NC CLIMP1 − CLIMP2 − BST1 RS1 BG + 4.0V CS1 CSN1 _ VDRV CS 1_INT Vcc_rdy V1 − Startup INPUT UVLO VCC VDRV CS 1 TS + 4.0V CSP1 Thermal Shutdown CONFIG VCC CSP1 BG + DBIN PWM CLIND PG V2 VSW1 VDRV RS2 LSG1 CO TS CLINDP2 + CS 2 Q1 CO 2 PGND1 OV EN Q2 CLIND CLIND PG_Low EN _MASK ENPOL OV_MSK + VFB − PG_MSK − EN + ADC Value Register SDA SCL Analog Mux CFET PDRV CSP1 VFB CS 1_INT CS 2_INT PG_High + PG VFB CSP2 + Limit Registers OV_REF − CS 2 CONFIG I2C Interface OV PG/ OV/ LOGIC CSN2 CS 2_INT CSN2 Digital Configuration INT CS 2_INT Oscillator Reference INT Interface COMP Status Registers PDRV Buck Control Logic VFB CP CFET VDRV PDRV PWM + CC VDRV CFET BG Error OTA PG TS _ EN LOGIC 0.8V + EN Rbld − VOUT _ FB RC VFB R1 AGND FLAG Figure 4. Block Diagram Table 1. PIN FUNCTION DESCRIPTION Pin Pin Name Description 1 HSG1 S1 gate drive. Drives the S1 N−channel MOSFET with a voltage equal to VDRV superimposed on the switch node voltage VSW1. 2 LSG1 Drives the gate of the S2 N−channel MOSFET between ground and VDRV. 3, 22 PGND Power ground for the low side MOSFET drivers. Connect these pins closely to the source of the bottom N−channel MOSFETs. 4 CSN1 Negative terminal of the current sense amplifier. 5 CSP1 Positive terminal of the current sense amplifier. 6 V1 7 CS1 8 CLIND 9 SDA I2C interface data line. 10 SCL I2C interface clock line. 11 INT Interrupt is an open drain output that indicates the state of the output power, the internal thermal trip, and other I2C programmable functions. 12 CFET Controlled drive of an external MOSFET that connects a bulk output capacitor to the output of the power converter. Necessary to adhere to low capacitance limits of the standard USB Specifications for power prior to USB PD negotiation. 13, 14 AGND The ground pin for the analog circuitry. 15 COMP Output of the transconductance amplifier used for stability in closed loop operation. Input voltage of the converter Current sense amplifier output. CS1 will source a current that is proportional to the voltage across CSP1/CSN1. Connect CS1 to a high impedance monitoring input. Open drain output to indicate that the CS1 or CS2 voltage has exceeded the I2C programmed limit. www.onsemi.com 4 NCP81231 Table 1. PIN FUNCTION DESCRIPTION (continued) Pin Pin Name Description 16 EN Precision enable starts the part and places it into default configuration when toggled. 17 PDRV The open drain output used to control a PMOSFET or connect to an external resistor. 18 CS2 19 FB 20 CSN2 Negative terminal of the current sense amplifier. Used for DCR sensing. 21 CSP2 Positive terminal of the current sense amplifier. Used for DCR sensing. 23−25 NC Current sense amplifier output. CS2 will source a current that is proportional to the voltage across CSP1/CSN1. Connect CS2 to a high impedance monitoring input. Feedback voltage of the output, negative terminal of the gm amplifier. No connection. 26 VOUT 27 DBOUT Connect to the buck output voltage. 28 DBIN The dead battery input to the converter where 5 V is applied. A 1 mF capacitor should be placed close to the part to decouple this line. 29 VDRV Internal voltage supply to the driver circuits. A 1 mF capacitor should be placed close to the part to decouple this line. 30 VCC 31 VSW1 Switch Node. VSW1 pin swings from a diode voltage drop below ground up to V1. 32 BST1 Driver Supply. The BST1 pin swings from a diode voltage below VDRV up to a diode voltage below V1 + VDRV. Place a 0.1 mF capacitor from this pin to VSW1. 33 THPAD The output of the dead battery circuit which can also be used for the VCONN voltage supply. The VCC pin supplies power to the internal circuitry. The VCC is the output of a linear regulator which is powered from V1. Can be used to supply up to a 100 mA load. Pin should be decoupled with a 1 mF capacitor for stable operation. Center pad, recommended to connect to AGND. Table 2. MAXIMUM RATINGS (Over operating free−air temperature range unless otherwise noted) Rating Symbol Min Max Unit Input of the Dead Battery Circuit DBIN −0.3 5.5 V Output of the Dead Battery Circuit DBOUT −0.3 5.5 V Driver Input Voltage VDRV −0.3 5.5 V Internal Regulator Output VCC −0.3 5.5 V Output of Current Sense Amplifiers CS1, CS2 −0.3 3.0 V Current Limit Indicator CLIND −0.3 VCC + 0.3 V Interrupt Indicator INT −0.3 VCC + 0.3 V Enable Input EN −0.3 5.5 V I2C SDA, SCL −0.3 VCC + 0.3 V Compensation Output COMP −0.3 VCC + 0.3 V V1 Power Stage Input Voltage V1 −0.3 32 V, 40 V (20 ns) V Positive Current Sense CSP1 −0.3 32 V, 40 V (20 ns) V Negative Current Sense CSN1 −0.3 32 V, 40 V (20 ns) V Positive Current Sense CSP2 −0.3 32 V, 40 V (20 ns) V Negative Current Sense CSN2 −0.3 32 V, 40 V (20 ns) V Feedback Voltage FB −0.3 5.5 V CFET Driver CFET −0.3 VCC + 0.3 V Driver Positive Rail BST1 −0.3 V wrt/PGND −0.3 V wrt/VSW 37 V, 40 V (20 ns) wrt/PGND 5.5 V wrt/VSW V Communication Lines www.onsemi.com 5 NCP81231 Table 2. MAXIMUM RATINGS (continued) (Over operating free−air temperature range unless otherwise noted) Rating Symbol Min Max Unit High Side Driver HSG1 −0.3 V wrt/PGND −0.3 V wrt/VSW 37 V, 40 V (20 ns) wrt/GND 5.5 V wrt/VSW V Switching Node and Return Path of Driver VSW1 −5.0 V 32 V, 40 V (20 ns) V Low Side Driver LSG1 −0.3 V 5.5 V PMOSFET Driver PDRV −0.3 40 V Voltage Differential AGND to PGND −0.3 0.3 V CSP1−CSN1, CSP2−CSN2 Differential Voltage CS1DIF, CS2DIF −0.5 0.5 V PDRV Maximum Current PDRVI 0 10 mA PDRV Maximum Pulse Current (100 ms on time, with > 1 s interval) PDRVIPUL 0 200 mA Maximum VCC Current VCCI 0 80 mA Operating Junction Temperature Range (Note 1) TJ −40 150 °C Operating Ambient Temperature Range TA −40 100 °C Storage Temperature Range TSTG −55 150 °C Thermal Characteristics (Note 2) QFN 32 5mm x 5mm Maximum Power Dissipation @ TA = 25°C Thermal Resistance Junction−to−Air with Solder PD RQJA Lead Temperature Soldering (10 sec): Reflow (SMD styles only) Pb−Free (Note 3) RF 4.1 30 W °C/W 260 Peak °C Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality should not be assumed, damage may occur and reliability may be affected. 1. The maximum package power dissipation limit must not be exceeded. 2. The value of QJA is measured with the device mounted on a 3in x 3in, 4 layer, 0.062 inch FR−4 board with 1.5 oz. copper on the top and bottom layers and 0.5 ounce copper on the inner layers, in a still air environment with TA = 25°C. 3. 60−180 seconds minimum above 237°C. Table 3. ELECTRICAL CHARACTERISTICS (V1 = 12 V, Vout = 5.0 V , TA = +25°C for typical value; −40°C < TA < 100°C for min/max values unless noted otherwise) Symbol Parameter Test Conditions Min Typ Max Units 28 V 5.5 V Power Supply V1 Operating Input Voltage V1 4.5 VDRV Operating Input Voltage VDRV 4.5 VCC UVLO Rising Threshold VCCSTART UVLO Hysteresis for VCC VCCVHYS VDRV UVLO Rising Threshold VDRVSTART Falling Hysteresis 5 4.26 V 320 mV 4.27 V 340 mV 5 V 160 mV 97 mA UVLO Hysteresis for VDRV VDRVHYS Falling Hysteresis VCC Output Voltage VCC With no external load VCC Drop Out Voltage VCCDROOP 30 mA load VCC Output Current Limit IOUTVCC VCC Loaded to 4.3 V V1 Shutdown Supply Current IVCC_SD EN = 0 V, 4.2 V ≤ V1 ≤ 28 V 6.7 VDRIVE Switching Current Buck IV1_SW EN = 5 V, Cgate = 2.2 nF, VSW = 0 V, FSW = 600 kHz 15 www.onsemi.com 6 4.96 80 7.7 mA mA NCP81231 Table 3. ELECTRICAL CHARACTERISTICS (continued) (V1 = 12 V, Vout = 5.0 V , TA = +25°C for typical value; −40°C < TA < 100°C for min/max values unless noted otherwise) Parameter Symbol Test Conditions Min Typ Max Units 0.5 1.2 2.0 0.505 1.212 2.02 V Voltage Output Voltage Output Accuracy VFB DAC_TARGET = 00110010 DAC_TARGET = 01111000 DAC_TARGET = 11001000 0.495 1.188 1.98 Voltage Accuracy Over Temperature VOUTERT −40°C < TA < 100°C VFB > 0.5 V VFB < 0.5 V −1.0 −5 1.0 5 % mV TA = 25°C VFB > 0.5 V −0.45 0.45 % VOUTER Transconductance Amplifier Gain Bandwidth Product GBW 3 db (Note 4) 5.2 MHz Transconductance GM1 Default 500 mS Max Output Source Current limit GMSOC 60 83 mA Max Output Sink Current limit GMSIC 60 84 mA Voltage Ramp Vramp 1.4 V Internal BST Diode Forward Voltage Drop VFBOT IF = 10 mA, TA = 25°C Reverse−Bias Leakage Current DIL BST−VSW UVLO BST−VSW Hysteresis 0.35 0.46 0.55 V BST−VSW = 5 V VSW = 28 V, TA = 25°C 0.05 1 mA BST1_UVLO Rising (Note 4) 3.5 V BST_HYS (Note 4) 300 mV FSW_0 FSW = 000, default 528 600 672 kHz FSW_1 FSW = 001 132 150 168 kHz FSW_7 FSW = 110 1056 1200 1344 kHz 12 % Oscillator Oscillator Frequency Oscillator Frequency Accuracy FSWE −12 Minimum On Time MOT Measured at 10% to 90% of VCC, −40°C < TA < 100°C 50 ns Minimum Off Time MOFT Measured at 90% to 10% of VCC, −40°C < TA < 100°C 90 ns Interrupt Low Voltage VINTI IINT(sink) = 2 mA Interrupt High Leakage Current INII 3.3 V Interrupt Startup Delay INTPG Soft Start end to PG positive edge 2.1 ms Interrupt Propagation Delay PGI Delay for power good in 3.3 ms PGO Delay for power good out 100 ns PGTH Power Good in from high 105 % PGTH Power Good in from low 95 % PGTHYS PG falling hysteresis 2.5 % 140 % INT Thresholds Power Good Threshold FB Overvoltage Threshold FB_OV Overvoltage Propagation Delay VFB_OVDL 3 1 Cycle 4. Ensured by design. Not production tested. www.onsemi.com 7 0.2 V 100 nA NCP81231 Table 3. ELECTRICAL CHARACTERISTICS (continued) (V1 = 12 V, Vout = 5.0 V , TA = +25°C for typical value; −40°C < TA < 100°C for min/max values unless noted otherwise) Parameter Symbol Test Conditions Min Typ Max Units External Current Sense (CS1,CS2) 500 mA 5 mS Positive Current Measurement High CS10 CSP1−CSN1 or CSP2−CSN2 = 100 mV Transconductance Gain Factor CSGT Current Sense Transconductance Vsense = 1 mV to 100 mV Transconductance Deviation CSGE Current Sense Common Mode Range CSCMMR −3dB Small Signal Bandwidth CSBW Input Sense Voltage Full Scale ISVFS CS Output Voltage Range CSOR VSENSE = 100 mV Rset = 6k Current Limit Indicator Output Low CLINDL Input current = 500 mA Current Limit Indicator Output High CLINDH Input current = 500 mA 4.0 5.0 Internal Current Sense Gain for PWM ICG CSPx−CSNx = 100 mV 9.2 9.9 10.5 V/V Positive Peak Current Limit Trip PPCLT INT_CL = 00 34 39 44 mV Negative Valley Current Limit Trip NVCLT INT_CL_NEG = 00 31 40 45 mV HSG Pullup Resistance HSG_PU BST−VSW = 4.5 V 2.9 W HSG Pulldown Resistance HSG_PD BST−VSW = 4.5 V 1.1 W LSG Pullup Resistance LSG_PU LSG −PGND = 2.5 V 3.4 W LSG Pulldown Resistance LSG_PD LSG −PGND = 2.5 V 1.1 W HSG Falling to LSG Rising Delay HSLSD 15 ns LSG Falling to HSG Rising Delay LSHSD 15 ns VCC V −20 20 % 3 28 V VSENSE (AC) = 10 mVPP, RGAIN = 10 kW (Note 4) 30 0 MHz 100 mV 3 V 100 mV External Current Limit (CLIND) 10 V Internal Current Sense Switching MOSFET Drivers CFET CFET Drive Voltage CFETDV Source/Sink Current CFETSS CFET clamped to 2 V 2 mA Pull Down Delay CFETD Measured at 10% to 90% of VCC, −40°C < TA < 100°C 10 ms CFET Pull Down Resistance CFETR Measured with 1 mA Pull up Current, after 10 ms rising edge delay 1.3 kW Charge Slew Rate SLEWP Slew = 00, FB = 0.1 VOUT Slew = 11, FB = 0.1 VOUT 0.6 4.8 mV/ms Discharge Slew Rate SLEWN Slew = 00, FB = 0.1 VOUT Slew = 11, FB = 0.1 VOUT −0.6 −4.8 mV/ms Slew Rate/Soft Start Dead Battery/VCONN Dead Battery Input Voltage Range VDB Dead Battery Output Voltage VIO Dead Battery Current Limit DB_LIM 4.5 5 5.25 V VDB = 5 V, −40°C < TA < 100°C, Output Current 32 mA 4 4.7 5 V VDB = 5 V, V1 greater than 2 V 29 57 4. Ensured by design. Not production tested. www.onsemi.com 8 mA NCP81231 Table 3. ELECTRICAL CHARACTERISTICS (continued) (V1 = 12 V, Vout = 5.0 V , TA = +25°C for typical value; −40°C < TA < 100°C for min/max values unless noted otherwise) Parameter Symbol Test Conditions Min Typ Max Units 800 820 mV Enable EN High Threshold Voltage ENHT EN Low Threshold Voltage ENLT EN Pull Up Current IEN_UP EN Pull Down Current IEN_DN EM_MASK = ENPU = ENPOL = 0 640 667 mV EN = 0 V 5 mA EN = VCC 5 mA I2C Interface Voltage Threshold I2CVTH 0.95 Propagation Delay I2CPD (Note 4) Communication Speed I2CSP (Note 4) 1 1.05 25 V ns 1 MHz Internal ADC Range ADCRN LSB Value ADCLSB (Note 4) 0 2.55 Error ADCFE (Note 4) Thermal Shutdown Threshold TSD (Note 4) 151 °C Thermal Shutdown Hysteresis TSDHYS (Note 4) 28 °C 20 V mV 1 LSB Thermal Shutdown PDRV 0 PDRV Operating Range 28 V PDRV Leakage Current PDRV_IDS FET OFF, VPDRV = 28 V 480 nA PDRV Saturation Voltage PDRV_VDS ISNK = 10 mA 0.20 V Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be indicated by the Electrical Characteristics if operated under different conditions. 4. Ensured by design. Not production tested. www.onsemi.com 9 NCP81231 APPLICATION INFORMATION Feedback and Output Voltage Profile voltage to 5 V in default. The reference voltage can be adjusted with 10 mV(default) or 5 mV steps from 0.3 V to 2.55 V through the voltage profile register (01H), which makes the continuous output voltage profile possible through an external resistor divider. For example, if the external resistor divider has a 10:1 ratio, the output voltage profile will be able to vary from 3 V to 25.5 V with 100 mV steps but not above V1 voltage. The feedback of the converter output voltage is connected to the FB pin of the device through a resistor divider. Internally FB is connected to the inverting input of the internal transconductance error amplifier. The non−inverting input of the gm amplifier is connected to the internal reference. The internal reference voltage is by default 0.5 V. Therefore, for example, a 10:1 resistor divider from the converter output to the FB will set the output Table 4. VOLTAGE PROFILE SETTINGS dac_taget dac_target_LSB Voltage Profile Hex Value Reference Voltage (mV) 0 0 00H Reserved 0 0 1 00H Reserved 0 0 1 0 01H Reserved … … … … … … … 1 1 1 0 1 1 1DH Reserved 0 1 1 1 1 0 0 1EH 300 0 1 1 1 1 0 1 1EH 305 … … … … … … … … … … 0 0 1 1 0 0 1 0 0 32H 500 (Default) … … … … … … … … … … … 1 1 0 0 1 0 0 0 0 C8H 2000 … … … … … … … … … … … 1 1 1 1 1 1 1 1 0 FFH 2550 1 1 1 1 1 1 1 1 1 FFH 2555 bit_8 bit_7 bit_6 bit_5 bit_4 bit_3 bit_2 bit_1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 … … … … 0 0 0 0 0 0 0 … 1000 mS allowing the DC gain of the system to be increased more than a decade triggered by the adding and removal of the bulk capacitance or in response to another user input. The default transconductance is 500 mS. Transconductance Voltage Error Amplifier To maintain loop stability under a large change in capacitance, the NCP81231 can change the gm of the internal transconductance error amplifier from 87 mS to Table 5. AVAILABLE TRANSCONDUCTANCE SETTING AMP_2 AMP_1 AMP_0 Amplifier GM Value (mS) 0 0 0 87 0 0 1 100 0 1 0 117 0 1 1 333 1 0 0 400 1 0 1 500 1 1 0 667 1 1 1 1000 www.onsemi.com 10 NCP81231 Programmable Slew Rate The slew rate of the NCP81231 is controlled via the I2C registers with the default slew rate set to 0.6 mV/ms (FB = 0.1 VOUT, assume the resistor divider ratio is 10:1) which is the slowest allowable rate change. The slew rate is used when the output voltage starts from 0 V to a user selected profile level, changing from one profile to another, or when the output voltage is dynamically changed. The output voltage is divided by a factor of the external resistor divider and connected to FB pin. The 9 Bit DAC is used to increase the reference voltage in 10 or 5 mV increments. The slew rate is decreased by using a slower clock that results in a longer time between voltage steps, and conversely increases by using a faster clock. The step monotonicity depends on the bandwidth of the converter where a low bandwidth will result in a slower slew rate than the selected value. The available slew rates are shown in Table 6. The selected slew rate is maintained unless the current limit is tripped, in which case the increased voltage will be governed by the positive current limit until the output voltage falls or the fault is cleared. 2.56 V DAC_TARGET 9 bit DAC DAC_TARGET_LSB VREF COMP + VOUT − RC CI CC FB = 0.1*V2 Figure 5. Slew Rate Limiting Block Diagram and Waveforms voltage. If a prebias exists on the output and the converter starts in synchronous mode, the prebias voltage will be discharged. The NCP81231 controller ensures that if a prebias is detected, the soft start is completed in a non−synchronous mode to prevent the output from discharging. Table 6. SLEW RATE SELECTION Slew Bits Soft Start or Voltage Transition (FB = 0.1*VOUT) Slew_0 0.61 mV/ms Slew_1 1.2 mV/ms Slew_2 2.4 mV/ms Frequency Programming Slew_3 4.9 mV/ms The switching frequency of the NCP81231 can be programmed from 150 kHz to 1.2 MHz via the I2C interface. The default switching frequency is set to 600 kHz. Once the part is enabled, the frequency is set and cannot be changed while the part remains enabled. The part must be disabled with no switching prior to writing the frequency bits into the appropriate I2C register. The discharge slew rate is accomplished in much the same way as the charging except the reference voltage is decreased rather than increased. Soft Start During a 0 V soft start, standard converters can start in synchronous mode and have a monotonic rising of output Table 7. FREQUENCY PROGRAMMING TABLE Name Bit Definition Freq1 03H [2:0] Frequency Setting Description 3 Bits that Control the Switching Frequency from 150 kHz to 1 MHz. 000: 600 kHz 001: 150 kHz 010: 300 kHz 011: 450 kHz 100: 750 kHz 101: 900 kHz 110: 1.2 MHz 111: Reserved www.onsemi.com 11 NCP81231 100% Duty Cycle Operation Current Sense Amplifiers NCP81231 can operate in a 100% duty cycle mode when the high side switch works as a bypass switch. A detection circuit will constantly monitor the high side gate voltage and turn on low side switch to refresh the boost capacitor when the voltage across the boost capacitor is below the boost UVLO voltage. If the system stays in the 100% duty cycle operation, the output will always follow the input regardless the COMP voltage and COMP is likely to creep up. If a fast COMP recovery is required, the following clamping circuitry can be considered with a larger than 1.5 V clamping voltage set as the target. Internal differential amplifiers measure the potential between the terminal CSP1/CSN1 or CSP2/CSN2. The potential difference between CSPx and CSNx is level shifted from the high voltage domain to the low voltage VCC domain. Both current sense signals can be monitored externally by CS1 and CS2 pins. They are fixed gm amplifier outputs, allowing users to set output gain by shunting resistors. CS1 correlates to the CSP1/CSN1 reading, CS2 correlates to the CSP2/CSN2 reading. When not used, CSP1/CSN pin can be shorted therefore CS1 reading is omitted. NCP81231 also uses CSP2/CSN2 current sense signal for current mode modulation and cycle by cycle positive and negative peak current limiting. The inputs of CSP2/CSN2 can be a current sense resistor or configured for inductor DCR sensing shown as Figure 7. A resistor Rs1 connects from switch node to CSP2 and Rs2 connects from the output voltage to CSN2 respectively. Two capacitors, Cs1 and Cs2, are common mode filtering capacitors from CSP2 and CSN2 to the ground. Choose Rs1=Rs2=Rs, Cs1=Cs2=Cs; In order to replicate inductor current sensing information, Rs*Cs needs to be equal or slightly higher than the ratio of output inductance over its DC resistance or L/DCR. Additional resistor network may be added to expand the actual current limit tripping range. VCC R2 NCP81231 D1 COMP R1 Figure 6. External Comp Clamping Circuit Internal Path 10x(CSP2-CSN2) + + − − − CLIP 10X + 10x(CSP2-CSN2) RAMP 1 RAMP 2 VCM + + − − Negative Current + Limit − CLIN CSP1/CSP2 Positive Current Limit CS1 or CS2 + ADC − + − CS2 MUX − CS1 MUX CSN1/CSN2 2 + VCC 2 CLIND CS2 CS1 CCS RCS CCS Figure 7. Block Diagram for Current Sense Channel www.onsemi.com 12 RCS NCP81231 S1 L SWN DCR RS1 VOUT RS2 CS1 CS2 S2 CSP2 CSN2 Figure 8. Inductor DCR Sensing Using CSP2/CSN2 Positive Current Limit Internal Path this way, current is limited on a pulse by pulse basis. Pulse by pulse current limiting is advantageous for limiting energy into a load in over current situations but are not up to the task of limiting energy into a low impedance short. To address the low impedance short, the NCP81231 will go to latch up mode if pulse by pulse current limiting continues for more than 4 cycles. Toggling the enable pin or resetting the input voltage (V1) will clear the latched OCP fault. The NCP81231 has a pulse by pulse current limiting function activated when a positive current limit triggers. When a positive current limit is triggered, the current pulse is truncated. For NCP81231, the CSP2/CSN2 pins will be the positive current limit sense channel. The S1 switch is turned off to limit the energy during an over current event. The current limit is reset every switching cycle and waits for the next positive current limit trigger. In Table 8. INTERNAL PEAK CURRENT LIMIT CLIP_1 CLIP_0 CLIM delta Value (mV) CSP2−CSN2 (mV) Trip Current Inductor DCR = 2 mW (A) 0 0 380 38 19 0 1 230 23 11.5 1 0 110 11 5.5 1 1 700 70 35 External Path (CS1, CS2, CLIND) The speed and accuracy of the dual amplifier stage allows the reconstruction of the input and output current signal, creating the ability to limit the peak current. If the user would like to limit the mean DC current of the switch, a capacitor can be placed in parallel with the RCS resistors. The external CS voltages are connected to 2 high speed low offset comparators. The comparators output can be used to suspend operation until reset or restart of the part depending on I2C configuration. When one of the comparators trips if not masked, the external CLIND flag is triggered to indicate that the internal comparator has exceeded the preset limit. The default comparator setting is 250 mV which is a limit of 500 mA with a current sense resistor of 5 mW and an RCS resistor of 20 kW. The block diagram in Figure 9 shows the programmable comparators and the settings are shown in Table 9. The voltage drop across CSP1/CSN1 or CSP2/CSN2 as a result of the load can be observed on the CS1 and CS2 pins. The voltage drop is converted into a current by a transconductance amplifier with a typical GM of 5 mS. The final gain of the output is determined by the end users selection of the RCS resistors or the inductor DCR resistor. The output voltage of the CS pin can be calculated from Equation 1. The user must be careful to keep the dynamic range below 3.0 V when considering the maximum short circuit current. V CS + (I LOAD_MAX * R SENSE * Trans) * R CS ³ ³ 2.967 V + (8.5 A * 5 mW * 5 mS) * 13.96 kW R CS + V CS ³ I LOAD * R SENSE * Trans ³ 13.96 kW + 2.967 V 8.5 A * 5 mW * 5 mS (eq. 1) www.onsemi.com 13 NCP81231 CS1 CS1 RCS2 CS2 CLIM MUX CS2_LIM CS2 Buffer + CS2 Resistor Network CLIND MUX − RCS2 Buffer − MUX BG + CS1 CS1_LIM Figure 9. Block Diagram for CLIM Comparator Table 9. REGISTER SETTING FOR THE CLIM COMPARATORS Current at RSENSE = 5 mW Current at RSENSE = 5 mW RSET = 20 kW (A) RSET = 10 kW (A) 0.25 .5 1 0.75 1.5 3 0 1.5 3 6 1 2.5 5 10 CLIMx_1 CLIMx_0 CSx_LIM (V) 0 0 0 1 1 1 Overvoltage Protection (OVP) PG_MSK When the divided output voltage is 140% (typical) above the internal reference voltage, a latched OV fault will be triggered. At 0 V reference voltage, it’s easy to trigger OVP falsely. So one should avoid using output voltage profile under 0.3 V for safety in normal operation. When 0 V output voltage is needed, one can disable NCP81231 by pulling EN pin down, instead of setting output voltage profile to 0 via I2C. Toggling the enable pin will not clear the latched OVP fault. Only resetting the input voltage (V1) can clear it. PG_Low − PG + VFB − PG_High + Figure 10. PG Block Diagram Power Good Monitor (PG) NCP81231 provides two window comparators to monitor the internal feedback voltage. The target voltage window is ±5% of the reference voltage (typical). Once the feedback voltage is within the power good window, a power good indication is asserted once a 3.3 ms timer has expired. If the feedback voltage falls outside a ±7% window for greater than 1 switching cycle, the power good register is reset. Power good is indicated on the INT pin if the related I2C register is set to display the PG state. During startup, INT is set until the feedback voltage is within the specified range for 3.3 ms. Table 10. POWER GOOD MASKING PG_MSK Description 0 PG Action and Indication Unmasked 1 PG Action and Indication Masked Thermal Shutdown The NCP81231 protects itself from overheating with an internal thermal shutdown circuit. If the junction temperature exceeds the thermal shutdown threshold (typically 150°C), all MOSFETs will be driven to the off state, and the part will wait until the temperature decreases to an acceptable level. The fault will be reported to the fault register and the INT flag will be set unless it is masked. When the junction temperature drops below 125°C (typical), the part will discharge the output voltage to 0 V. www.onsemi.com 14 NCP81231 CFET Turn On incorporates a right drive circuit that regulates current into the gate of the MOSFET such that the MOSFET turns on slowly reducing the drain to source resistance gradually. Once the transition from high to low has occurred in a controlled way, a strong pulldown driver is used to ensure normal operation does not turn on the power N−MOSFET engaging the bulk capacitance. The CFET must be activated through the I2C interface where it can be engaged and disengaged. The default state is to have the CFET disengaged. The CFET is used to engage the output bulk capacitance after successful negotiations between a consumer and a provider. The USB Power Delivery Specification requires that no more than 30 mF of capacitance be present on the VBUS rail when sinking power. Once the consumer and provider have completed a power role swap, a larger capacitance can be added to the output rail to accommodate a higher power level. The bulk capacitance must be added in such a way as to minimize current draw and reduce the voltage perturbation of the bus voltage. The NCP81231 VBUS HSG2 CBULK LSG2 30μF 10 μH QCFET VCC CFET 2μA CFET 10 ms Rising Edege Delay 2μA Figure 11. CFET Drive Table 11. CFET ACTIVATION TABLE CFET_0 Description 0 CFET Drive Pulldown 1 CFET Drive Pull Up VBUS PFET Drive The PMOS drive is an open drain output used to control the turn on and turn off of PMOSFET switches at a floating potential or to create an external discharging path. The RDSon of the pulldown NMOSFET is typically 20 W allowing the user to quickly turn on for a fast output discharge or to control the external pass FETs. PDRV PFET_DRV Table 12. PFET ACTIVATION TABLE PFET_DRV Description 0 NFET OFF (Default) 1 NFET ON Figure 12. PFET Drive www.onsemi.com 15 NCP81231 Analog to Digital Converter ADC, thus the range of the measurement is 0 V−2.55 V, same as FB. The resolution of the V1 and FB voltage is 20 mV at the analog mux, but since the voltage is divided by 10 output voltage resolution will be 200 mV. When CS1 and CS2 are sampled, the range is 0 V−2.55 V. The resolution will be 20 mV in the CS monitoring case. The actual current can be calculated by dividing the CS1 or CS2 values with the factor of Rsense*5mS*RCSx, the total gain from the current input to the external current monitoring outputs. The analog to digital converter is a 7−bit A/D which can be used as an event recorder, an input voltage sampler, output voltage sampler, input current sampler, or output current sampler. The converter digitizes real time data during the sample period. The internal precision reference is used to provide the full range voltage; in the case of input voltage V1 or the feedback voltage FB (with 10:1 external resistor divider) the full range is 0 V to 25.5 V. V1 is internally divided down by 10 before it is digitized by the Figure 13. Analog to Digital Converter Table 13. ADC BYTE DATA MSB 5 4 3 2 1 LSB D6 D5 D4 D3 D2 D1 D0 Table 14. REGISTER SETTING FOR ENABLING DESIRED ADC BEHAVIOUR ADC_2 ADC_1 ADC_0 Description 0 0 0 Sets Amux to VFB 0 0 1 Sets Amux to V1 0 1 0 Sets Amux to CS2 0 1 1 Sets Amux to CS1 1 0 0 Select all in rotating sequence (VFB, V1, CS2, CS1, VFB, …) www.onsemi.com 16 NCP81231 Interrupt Control The interrupt controller continuously monitors internal interrupt sources, generating an interrupt signal when a system status change is detected. Individual bits generating interrupts will be set to 1 in the INTACK register (I2C read only registers), indicating the interrupt source. All interrupt sources can be masked by writing 1 in register INTMSK. Masked sources will never generate an interrupt request on the INT pin. The INT pin is an open drain output. A non−masked interrupt request will result in the INT pin being driven high. Figure 14 illustrates the interrupt process. OV OV OV_MASK SHUTDN OV _REG SHUTDN_MASK TEMP PG TEMP_MASK INT PG PG_MASK PG_REG INTOCP INTOCP_MASK TEMP EXTOC EXTOC_MASK INTACK TEMP_REG INTACK_MASK VCHN INT VCHN_MASK Figure 14. Interrupt Logic Table 15. INTERPRETATION TABLE Interrupt Name OV Shutdown TEMP PG I2C Address Description NCP81231 has two address selectable factory settings. The default address is set to 77h. Output Over Voltage Shutdown Detection (EN=low) IC Thermal Trip Power Good Trip Thresholds Exceeded INTOCP Internal Current Limit Trip EXTOC External Current Trip from CLIND VCHN Output Negative Voltage Change INTACK I2C ACK signal to the host Table 16. I2C ADDRESS I2C Address Hex A6 A5 A4 A3 A2 A1 A0 ADD0 (default) 0x77 1 1 1 0 1 1 1 ADD1 0x76 1 1 1 0 1 1 0 www.onsemi.com 17 NCP81231 I2C interface external processor by means of a serial link using a 400 kHz up to 1.2 MHz I2C two−wire interface protocol. The I2C interface provided is fully compatible with the Standard, Fast, and High−Speed I2C modes. The NCP81231 is not intended to operate as a master controller; it is under the control of the main controller (master device), which controls the clock (pin SCL) and the read or write operations through SDA. The I2C bus is an addressable interface (7−bit addressing only) featuring two Read/Write addresses. The I2C interface can support 5 V TTL, LVTTL, 2.5 V and 1.8 V interfaces with two precision SCL and SDA comparators with 1V thresholds shown in Figure 15. The part cannot support 5 V CMOS levels as there can be some ambiguity in voltage levels. I2C Compatible Interface The NCP81231 can support a subset of I2C protocol as detailed below. The NCP81231 communicates with the 5V CMOS Vcc =4.5V−5.5V TTL Vcc =4.5V−5.5V V OH = 4.44V LVTTL Vcc =2.7V−3.6V EIS/JEDEC 8−5 V IH = 0.7*vcc VTH = 0.5* vcc V OH = 2.4V 2.5 Vcc =2.3V−2. 7V EIS/JEDEC 8−5 V OH = 2.4V VIH = 2.0V VIH = 2. 0V 1.8V Vcc =1.65V−1.95V EIS/JEDEC 8−7 VOH = 2. 0V VIH = 1.7V VOH = VCC−0.45V V IH = 0. 65*Vcc VIL = 0.8V VOL = 0.4V V IL = 0.7V VOL = 0.4V VIL = 0.3*vcc VTH = 1. 5V VIL = 0.8V VOL = 0.4V VOL = 0.5V 1.0V Threshold V IL = 0.35*Vcc VOL = 0.45V Figure 15. I2C Thresholds and Comparator Thresholds I2C Communication Description The first byte transmitted is the chip address (with the LSB bit set to 1 for a Read operation, or set to 0 for a Write operation). Following the 1 or 0, the data will be: • In case of a Write operation, the register address (@REG) pointing to the register for which it will be written is followed by the data that will written in that location. The writing process is auto−incremental, so • the first data will be written in @REG, the contents of @REG are incremented, and the next data byte is placed in the location pointed to @REG + 1 ..., etc. In case of a Read operation, the NCP81231 will output the data from the last register that has been accessed by the last write operation. Like the writing process, the reading process is auto−incremental. From MCU to NCP81231 From NCP81231 to MCU Start 1 IC ADDRESS 1 ACK DATA 1 ACK Data n ACK DATA 1 ACK Data n /ACK STOP READ OUT FROM PART Read /ACK Start IC ADDRESS 0 STOP Write Inside Part ACK If part does not Acknowledge, the /NACK will be followed by a STOP or Sr. If part Acknowledges, the ACK can be followed by another data or STOP or Sr. 0 Write Figure 16. General Protocol Description www.onsemi.com 18 NCP81231 Read out from part then start or a repeated start will initiate the Read transaction from the register address the initial Write transaction was pointed to: The master will first make a “Pseudo Write” transaction with no data to set the internal address register. Then, a stop From MCU to NCP81231 From NCP81231 to MCU Start 0 IC ADDRESS 0 Sets Internal Register Pointer Register Address ACK ACK STOP Write Start IC ADDRESS 1 ACK DATA 1 ACK Data n /ACK STOP Write Inside Part Register Address + (n+1) Value Register Address Value N Register Read 0 Read Figure 17. Read Out From Part From MCU to NCP81231 From NCP81231 to MCU Start IC ADDRESS 0 Sets Internal Register Pointer Write Value in Register REG0 + (n−1) Write Value in Register REG0 ACK Register REG0 Address ACK REG Value REG + (n−1) Value ACK N Register Read 0 Write Start IC ADDRESS 1 ACK DATA 1 ACK Data n /ACK STOP Register Address +(n+1)+ (k−1) Value Register Address + (n−1) Value k Register Read 0 Read Figure 18. Write Followed by Read Transaction www.onsemi.com 19 ACK STOP NCP81231 Write in part register desired to access, the following data will be the data written in Reg, Reg + 1, Reg + 2, ..., Reg +n. Write operation will be achieved by only one transaction. After the chip address, the MCU first data will be the internal From MCU to NCP81231 From NCP81231 to MCU Start IC ADDRESS 0 Write Value in Register REG0 + (n−1) Write Value in Register REG0 Sets Internal Register pointer ACK Register REG0 Address ACK REG Value ACK N Register Read 0 Write Figure 19. Write in n Registers www.onsemi.com 20 REG + (n−1) Value ACK STOP NCP81231 PACKAGE OUTLINE QFN32 5x5, 0.5P CASE 485CE ISSUE O A B D ÉÉÉ ÉÉÉ ÉÉÉ PIN ONE REFERENCE 0.15 C L1 DETAIL A ALTERNATE CONSTRUCTIONS E TOP VIEW DETAIL B DIM A A1 A3 b D D2 E E2 e K L L1 ÉÉÉ ÇÇÇ ÇÇÇ EXPOSED Cu 0.15 C NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b APPLIES TO PLATED TERMINAL AND IS MEASURED BETWEEN 0.15 AND 0.30 MM FROM THE TERMINAL TIP. 4. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. L L (A3) MOLD CMPD DETAIL B 0.10 C ALTERNATE CONSTRUCTION A 0.08 C NOTE 4 A1 SIDE VIEW C SEATING PLANE RECOMMENDED SOLDERING FOOTPRINT* D2 DETAIL A MILLIMETERS MIN MAX 0.80 1.00 −−− 0.05 0.20 REF 0.20 0.30 5.00 BSC 3.40 3.60 5.00 BSC 3.40 3.60 0.50 BSC 0.20 −−− 0.30 0.50 −−− 0.15 K 8 5.30 3.70 17 32X 0.62 E2 32X 24 1 32 L 25 e e/2 3.70 32X BOTTOM VIEW b 0.10 M C A-B B 0.05 M C 5.30 NOTE 3 0.50 PITCH 32X 0.30 DIMENSIONS: MILLIMETERS *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. 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